I'm at about 30 months now. So it's about time for an update.
I'm at the point where on the typical good day when I go for a long walk I feel fairly close to normal. My balance isn't perfect and I still have a little waviness in my head, but the intensity is low and it's not there all the time. When I'm VERY active (like running, jumping, turning quickly, playing tennis) the intensity of the waviness increases fairly sharply, but it's still way better than it used to be. It also increases when I get tired.
About the only difference I can identify over the last few months is that if I rated my days as good or bad, a higher percentage of my days are of the good variety.
I did sort of hit a new short term peak today (which prompted me to give the update), but it didn't last long.
It was beautiful in NY today so I decided to play a little tennis. Tennis is tough. I can play, but I do feel the waviness when I'm running and I also usually have a little trouble following a rapidly moving tennis ball. But today I was running and playing tennis and felt about as close to normal as I have since surgery. It was easy to follow the ball. It was very exhilarating.
A couple of hours later I was back to "my normal", but I'd have to say that even at 30 months I think I am still making forward progress. It's so slow, it's hard to notice, but something is still going on otherwise I wouldn't have had such a peak day.